In a case where an in-car power supply unit used in a hybrid car or an electric car is disposed in, for example, an engine room, when dust or a liquid such as water, water droplet, rain water, sea water, a radiator liquid, and engine oil intrudes into the power supply unit, there is a possibility that an internal circuit may be damaged. For this reason, there has been a demand for improving the airtightness for a penetration-type terminal block that is attached to a casing of the power supply unit and electrically connected to an external device. In the penetration-type terminal block of which the airtightness is improved, as shown in Japanese Patent Application Laid-Open No. 2007-73449 and Japanese Patent Application Laid-Open No. H06-29052, a structure is disclosed which keeps airtightness between a casing and a conductive member by a resin that covers the conductive member.